Heteropoly acids or salts thereof as catalysts



Patented Aug. 26, 1952 HETEROPOLY ACIDS R SALTS THEREOF AS CATALYSTSRaymond N. Fleck, Long Beach, Calif., assignor to Union Oil Company ofCalifornia, Los Angelcs, Calif., a corporation of California No Drawing.Application April 18, 1949, Serial No. 88,224

is Claims. (01. 252-435) This invention relates to catalysts andcatalytic processes for processing various hydrocarbons and hydrocarbonmixtures. More particularly the invention relates to new and improvedcatalysts to be employed in these hydrocarbon conversion processes andfurther to the methods of preparing these catalysts.

The treatment of various hydrocarbons with catalysts to produce changestherein is well known in the art. The particular catalysts employed,temperatures and pressures of operation and other related factors serveto determine particular reactions taking place in the hydrocarbon feed.Many of these processes utilize a solid catalyst of granular, pelleted,powdered or other form, and for this reason these processes are termedheterogeneous catalytic conversion processes. Included in this group forexample, are catalytic cracking, dehydrogenation, hydrogenation,desulfurization, hydroforming, aromatization, certain alkylation andisomerization processes, addition reactions and the like. For theseprocesses many catalysts have been employed with varying success. Inmost cases, although such is not always the case, these catalystscomprise a catalytic agent distended on a suitable carrier or support.Such catalytic agents have included the oxides or other compounds of themetals such as chromium, molybdenum, cobalt, nickel, zinc, lead,cadmium, vanadium, manganese, tantalum, tungsten, titanium, platinum,columbium, scandium, thorium, uranium, zirconium, tin, copper, etc,which compounds may be produced by an appropriate treatment of thechromates, molybdates, vanadates, sulfates, nitrates, chlorides andother suitable salts of the metals by methods well known in the art.Many of these catalytic agents are effective only when supported on suchcarriers as alumina, magnesia, magnesium hydroxide, silica, zirconia,titania, zinc oxide, thoria, or a combination of one or more of these.Certain of these processes, however, may employ a catalyst comprisingpredominantly a catalytic agent in the absence of a carrier orsupporting material. Thus, for example, a desulfurization process may beaffected in the presence of a catalyst comprising the combined oxides ofcobalt and molybdenum, i e.

cobalt molybdate, in powdered, pelleted or gran=- ular form in theabsence of the alumina-silica carrier. However, catalysts supported onsuch a carrier are generally found to be equally and in many instancesmore effective than those catalysts consisting entirely of the catalyticagent and at the same time are considerably less expensive.

Many methods of preparation of these heterogeneous catalysts have beenutilized including impregnation, ooprecipitation, mechanical mixing,sublimation and the like. In preparing such a catalyst by impregnationthe carrier in the form of powder, granules or pellets is immersed in asolution of a suitable soluble salt of a desired metal such as ammoniummolybdate, chromium nitrate, ammonium dichromate, ammonium vanadate,-ammonium tungstate, cobalt nitrate, and the like, whereupon the carrierhaving adsorbed a portion of the solution. is dried and calcined at ateperature in the range of about 400 C. to about 700 C. to convert theadsorbed salt to the oxide of the metal or metals employed. In preparinga catalyst by coprecipitation the process embodies a simultaneous precipitationof the hydrated oxide of the carrier and the hydrated oxide oroxides of the desired catalytic agents from a solution containingappropriate amounts of suitable soluble salts of the carrier typematerial and the metal or metals employed as catalytic agent. Amodification of this procedure consists of precipitating the hydrousoxides of the catalytic agents in the presonce of a wet carrier gel.

There are certain factors which need be critically examined whenselecting the catalyst to be employed in any of the hydrocarbonconversion processes including, the expense of the catalyst; therelative activity of the particular catalyst in comparison to otherswhich may be employed; the mechanical strength of the catalyst particlesor granules and the effective life of the catalyst at the conditions oftemperature and pressure employed in the operation. Each of thesefactors are interrelated and a deficiency in one may be compensated forby relative proficiency in one Or more of the others. However,

one of the most important of these is the life of the catalyst inoperation.

The catalyst life appears to be a function of its composition and thetemperatures to which it is subjected and it is toward the former ofthese that the present invention is primarily directed. A laboratoryevaluation procedure for measuring the relative life expectancy of acatalyst has been developed and is widely used in the art. Thisprocedure consists in subjecting samples of the catalyst in question tohigh temperature heat treatments for given periods of time andsubsequently ascertaining the activity of the heat treated catalyst inrelation to the activity of the catalyst prior to this heat treatment.Exact predication of the catalyst life on the basis ofthese heattreatments is as yet im- 3 possible, but it has been found that therelative life expectancy of the various catalysts may be determined by acomparison of their heat stability characteristics.

During extended usage of catalysts of the type described a gradual lossin catalyst activity occurs which is generally accompanied by otherchanges of a physical nature such as loss of mechanical strength,decrease in eflective sunface area, changes in the pore sizedistribution and the like. The explanation for the loss in catalyticactivity and attendant changes is un certain and in any casecomparatively-complex but it is apparently tied up with variousoperatlonal factors such as the temperature, :both of.

the reaction and the regeneration, cooling :rates and the like. It hasbeen found that these various changes in the catalyst can be induced byhigh temperature heat treatments for comparativelyshort periods of time..Thusonestandard measure of a catalysts expected life characteristics isobtained by heating a sample .of the 7 catalyst for a period of sixhours at a temperature of 800 C. The heat treated sample and a sample-ofthe fresh catalyst are then tested for activity in the particularreaction for which the catalyst was prepared and the loss inactivityexhibited by the heat treated catalyst is compared with results ofsimilar tests on other catalyst samples to give a picture of therelative stability of the catalyst under examination.

The exact causes for the degradation of a catalyst during continuedoperation or in the heat stability test as above described has not beendefinitely determined but it is commonly accepted thata change in thestructure of the catalyst or carrier plays at least a large part .inthis loss of activity. For example X-ray diffraction datahave shown thatthe loss of activity of an alumina-supported catalyst is accompanied bya crystalgrowth within the catalyst and a resultant destruction of thegamma or more active form of alumina. However, in the absence ofa-cataly'tic agent, such an alumina carrier is stable with respect tothe destruction of the gamma 'alumina'at temperatures ashigh as 1,000 E.'But'this efiect is considerably altered when aicata'lyticagentisdistended on thesame aluminaand it is with this aspect of the catalystproblem that the present invention is primarily concerned. Apparentlythe effect of a catalytic agent on the alumina or 'on other carriers isto accelerateor possibly'even catalyzelthe crystal growth, theloss insurface area and other related factorswhich'may contribute to the lossin catalyst activity.

This effect has been shown many times over and C particularly observablein catalyst surface area studies in which I have-foundthat aluminacontaining approximately 12% of ,distended molybdenum .oxide losessubstantially all of its surface area when measured by the method ofBrunauer, Emmett .& Teller (J. Am. Chem. Soc. 60, 309 (1938) employingnitrogen as the adsorbate after a six hourheat treatmentat 900" C. Inthe absencepjf the distended molybdenum oxide-however, 'the samealumina.will show a *thus destroying the activity of the carrier. presentinvention is based primarily on the prin- 4 the carrier, inasmuch as thelower the percentage of the catalytic agent, the greater will be theheat stability of the catalyst. This, however, is of limited value inthe present art inasmuch as it has been found that certain percentagesof the catalytic agent are necessary in order to attain an economicallyfeasible catalytic activity even at the expense of a catalyst of shorterlife. It may be postulated that the active catalytic agent present onthe alumina undergoes a reversible chemical reaction with the alumina,The

c'iple of distending on the support or carrier material a form of-thecatalytic agent which will "be incapable or at least less capable ofcatalyzing catalytic agents'have been .distended which subsurface .area,measured as above, .of ,approxim'atelyf162 square meters per. gram aftercalcinastitution-is made possible :byrthe improved heat stability of thecatalysts containing the.ca'-talytic agents .of :my invention.

Another object of the invention is .to-provide a class of catalysts inwhich the catalytic agent comprises a heteropoly acid or a metalsalt ofa heteropoly acid.

A still further-object of the present invention is to provide a methodof preparing catalysts for these'h-ydrocarbon conversion processeshaving improved heat stability characteristics which involves new andsimplified methods of synthesizing and utilizing the heteropoly acidswhich heretofore have requiredlong and tedious preparation methods. Itis emphasized, however, that the hereinafter disclosed catalysts-maybeprepared from heteropoly acids'by the methods of this'invention or othermethods regardlessof the origin and synthesis methods of heteropolyacids themselves.

Hydrocarbon conversion processes -'may be divided into various narrowerclassifications. The term conversion is a broadone and'connotates anychange in the structure of the molecules present in the feed stocks.These changes-vary depending upon the operating conditions andcatalystsemployed in the treatment of the stock. Thus in one class ofoperation the predominate reaction is hydrogen exchange, 1. e. additionof hydrogen to the hydrocarbon molecules, withdrawing hydrogen therefromor in some instances adding hydrogen to a portion ofthe feed at leastpartially at the expense of another portion of the feed. The processeswhich may be classed as hydrogen exchange processes includedehydrogenation, hydrogenation, hydroforming, 'aromatization anddesulfurization. This latter process maybe classed in this group byvirtue of the fact that the removal of the sulfur from the hydrocarbonmolecule is accompanied by the introduction of hydrogen to take its]place. (A second class of 1 processes although class'ifiable'inj theabove grouping is directed pri- "marily to a 'changein relative size ofthe molecules; Such processes may either reduce or increasethefmolecular sizexof the components of 'the feed and include theprocessesof cracking, falkylation, polymerization, condensation, and thelike-and on the'basis of their primary function may be termedfmolecularreforming processes. A third class or isomerization process is unique initself althoughof courseisomeri'zation takes place to a certain extentin the majority of the other Xhy'drocarbon'. conversion reactions, As:such, however, it is not the primary reaction in .these.otherprocesses. 'A fourth class of conversion process comprises theaddition :.reactions such as nitration,chlorination,.bromination,hydration and the like. l '1 .1 :"Whereas,the-present invention contemplates the use 'of the catalysts ashereinafter described .in any of thehydrocarlcon conversion reactions, Ihave found that they have particular utility intho'se,processesinvolving primarily hydrogen exchange includinghydroforming, hydrogenation, dehydrogenation, desulfurization andaromatization inasmuch as in general these processes utilizecatalysts'comprising a catalytic agent distended ion, a suitablecarrier. Further, either during the reaction period or the regenerationperiod the catalysts employed in these processes are usuallysubjected tocomparatively high tem- .peratures and as a consequence heatstability ofthe catalystsbecomes afactor of (majorimportance. V

. The, present invention comprises the use of the heteropoly acids orthesalts of the heteropoly acids as catalytic agents to beemployed as suchor distended. on a suitable carrier material to be used in the abovedescribed catalytic processes. Thestructure of the heteropoly acids isdifiicult of determination owing to the verylarge size of the molecule.The heteropoly acids may be best described as complex inorganicsubstances of high molecular, Weight in which two or more different acid"cations or oxides of metals or metal- ..loids areas sociated withvarying, frequently indeterminate'jamounts of combined Water as waterof,hydration. The molecular weightof these bodies may be as great as3,000 or higher and they are comprised essentially of nuclear cations ofsuch metals as copper, thorium, tin, cerium, cobalt, zirconium,titanium, and the like or such non-metals as boron, silicon, phosphorusand arsenic, surrounded by oxygen radicals of molybdenum, tungsten orvanadium. According to the work of Miolati (J; prakt. Chem. (2), 1908,7'7, "417) substantiated by Illingworth and Keggin (J. Chem. Soc. 1935,580) the typical acid atom of the heteropoly acid, that is, thephosphorus atom in phosphoheteropoly acids, the silicon atom insilico-heterop'oly acids, etc., is to be regarded as a central atom of anucleus. This central atom i's hyd'rated and attached to six oxygenatoms, thus HqPOa, HsSIOe, etc. The oxygenis linked to 'the nuclear atomof phosphorus, silica, boron, arsenic or" the like in the same way thatmoleculesof ammonia are bound to the metalatom in the metallic aminos.The oxygen atoms can be wholly or partially substitutedby radicals suchas-MoO, M0207, WOaWzOi, V2O5,"V2Oc. Thus we may formphosphomolybdicfacid, phosphoturrgstic acid, phosphovanadic acid and thelike. The reasons for the existence of so many of these heteropplyacidsare the possibilities of different ce'ntral atoms, and 'the presence ofthe different "acid radicals in the same molecule in varying degrees ofsaturation. Thus Imay employ phosphomolybdotung'stic acid in whichmolybdenum and tungsten containing radicals surround the centralphosphorus atom, silicomolybdovanadic acid, titanomolybdotungstic acidand the like. In general the acids comprise the central atom surroundedby six or twelve molybdenum, tungsten, or vanadium radicals dependingupon the oxidation state of the metal in the radical.

Further, I may employ the metal salts of these hete'ropoly acids ascatalytic agents "such asfor example, cobalt phosphomolybdate, cadmiumborotungstate, cadmium silicomolybdate; ferric silicomolybdate, ammoniumvanadomolybdate, zinc phosphomolybdate, and thelike. Y

I have found that by employing the-appropriate heteropoly acid inthepreparation of the catalyst of the typ described hereinbeforethat theactive catalytic agent is so boundby the central atom of the 'hetercpolyacid that the propensity to catalyze the destruction of the carrierduring usage or heat stability testsis greatly minimized and thestability of the car"- rier approached that of the carrier in theabsence of a catalytic agent. At the same time the presence of thecentral atom apparently has substantially no deleterious effect on theactivity of the catalyst towards promoting the particular reactiondesired, and in manycases ac tually enhances the activity thereof. Thechoice of the heteropoly acid to be employed is a function of thereaction to be catalyzed. Thus, as is well known, molybdenum oxide is aneffective catalytic agent when distended on an alumina carrier for thepromotion of the hydrocarbon conversion or hydrogen exchange reactionknown as hydrcforming. In like manner. I have found, that a heteropolyacid or acid salt in which molybdenum containing radicals predominatewhen distended upon an alumina carrier is an excellent catalyst for thissame reaction. and at the same time has a longer-effective catalyst lifeand correlatively a greater heat stability than does the, conventionalmolybdenum oxide on alumina hydroiorming catalyst. agents may includefor example phosphomolybdic acid, silicomolybdic acid, germanomolybdicacid, chromiomolybdic acid, zinc phosphomolybdate, aluminumphosphomolybdate, aluminum silicomolybdate, titanium phosphomolybdateand the like. Similarly the combined oxides of cobait and molybdenumdistended on a suitable support such as alumina has found application asa catalyst for the desulfurization of sulfur containing hydrocarbons andfor this purpose I have found that the cobalt salt of aheteropolymolybdic acid such as cobalt phosphomolybdate, cobaltsilicomolybdate, cobalt chromomolybdate, cobalt phosphomolybdovanadate,and the like, when distended on a similar carrier give a catalystequally, if not more active and possessed of a longer eifective life andgreater heat stability. "Other heteropoly acid catalysts may be employedfor other reactions such as dehydrogenation, aromatization, cracking,hydration, polymerization, hydrogenation and the like, and in general Ihave found it preferable to employ aheteropoly acid or a heteropoly acidsaltin which the predominant metal radical is the same as the preferablemetal oxide or other compound employed as the catalytic agent in theconven tionalcatalyst forthe same type of reaction.

In general I have foundthat it is preferable to employ a heteropolyacidas the catalytic agent Such catalytic whichzcontainsLthersame metalionfound to be --most eifective inrconventional catalysts .for the,particularqreaction to-be catalyzed. In-addition, -:,howev,er,'other'ions'contained in the heteropoly :acidswor'its salt appear to bebeneficial in the .final catalyst and by the use-of these acids many.groups'ofimetal ions which are incompatible in ordinary impregnationsolution may be, distended :on the carrier intone operation. For examplesuchions as beryllium aluminum, thorium and 'iron cannot :ordinarilyexist in solution with suchqionslas 'molybdate, tungstate and vanadate.due :to the precipitation therefrom of the hy- .,droxides, molybdates,tungstates or vanadates .of ,thesemetals. However, the-above metallicions may be added -Lt;heteropoly acid solutions with- .out formation ofa precipitate because of the complex-form of the molybdenum, tungsten,and vanadium ions. In this :manner a. soluble salt of f'the' abovemetals as for example the nitrates, chlorides, sulphates or thelike maybe added to-aqueous solutions of these heteropoly acids :yielding withat least a portion of the added .metal ion a metal salt of theparticular heteropoly.

acidor acids in'the solution. Further, if desired .thesoluble-salts ofthese metals may be added in-excess ofithe amount equivalent for saltformation with-the heteropoly acid Without formation of a precipitate.Thus for hydroforming, I have .found that catalysts comprisingphosphomolybdic .orsilicomolybdic acids distended on alumina are .themost effective. For such catalysts I may em- ;ploy from about 2% toabout 20% of the catalyticragent and about 80% to about 98% of thecarrier, but preferably the amount of catalytic agent onthecarriershould be in the range of about 5% to about Althoughphosphoand= silicomolybdic acidsare the'preferred acids forzuse inhydroforming .catalysts I have also found that the :titanomolybdic acid,germane- .moly-bdic acid, and others are also eflective. Further,certain of the salts of the molybdic acids such" as aluminumphosphomolybdate, beryllium phosphomolybdate, titanium phosphomolybdate,zirconium .phosphomolybdate, chromium phosphomolybdate aswellas thecorresponding salts of the silico-, titano-, germanoandstannomolybdatesarealso effective when employed as the catalytic agentsin hydroforming catalysts. Of these saltsrit appears that the aluminumphosphoand silicomolybdates and the chromium phospho-.andesilicomolybdates are the most effective.

*Foraromatization or dehydrogenation catalysts ,I have found that bestresults are obtained if the chromium ion is present in the salt or inthe acid either as the central ion of the heteropoly acid or as theaddition ion in the metalsalt of the heteropoly acid. ThusI may employcatalysts comprising such catalytic agents as chromomolybdic acid orsalts thereof, .chromovanadic acid, chromium 'phosphomolybdate, chromium.silicomolybdate, chromium phosphotungstate, chromium silicotungstate,chromium phosphomanadate, beryllium .chromomolybdate and the like,distended on a suitable carrier such as alumina, magnesia, thoria,titania, and the like, and of these the'preferableis alumina. In :thesecatalysts the catalytic agent may beemployed in amounts ranging'fromabout 3% to about 30% andpreferably in amounts ranging from about 25%-to about 15% with the complementary amount of the desiredcarrier.

In thedesulfurization of hydrocarbons employing asolid :typecatalystbest results have been obtained-employing the heteropoly acidsor other zinc .phosphovanadate, and the like.

:saltsfofwhich a cobalt ion is contained suchaas for; example, cobaltphosphomolybdate, cobalt silicomolybdate, @cob'altphosphomolybdovanadate in whichraportion of the molybdenum oxide-in aheteropoly molybdic acid isrreplaced by-vanadium, cobaltphosphotungstate, 1 cobalt *titanomolybdate, iandthel ike. Althou'ghthecob'alt containing agents .arethe preferred ones for-the'desulfurization-proces other of the heteropoly acids andsalts-and.particularly'those containing tungsten are effective catalyticagents .:such :as

for example .nickel stannotung'state, xstanno- .tungstic acid,phosphotungstic acid, nickel silicotungstate, nickel. horotungstate,germanotungstic molybdovanadate, stannic ph'osphotungstovanadate,'andthelike.

The catalysts according to the present invention containing as they do:catalyticallyactive agents in combined form possess 'greater'heatstability and longer effective catalytic li-fe,'in-

creasedactivity in manycases, lower oarbomdepositionwhen operating atrelatively high temperatures .and equally important the property-0'1permitting the usage of impure carrier materials.

As pointed out above catalytic agents as normally employed have "theeffect of accelerating the destruction'of the=catalytic properties ofthe carrier material employed when exposed to long periods of usage'orcomparatively'hightemperatures. Further, it has beenfoundfthatthepresence of certain'impurities in the carrier'such assodium oxide, calcium oxide, magnesium oxide andthe like eveninrelatively small amounts such as 1% to 5% or less has the effect in thepresence of the catalytic agent of still further acceleratingthispdestruction or degradationo'f thescarriermaterial. I havefound'thatiby the usage of the catalytic agents herein. describedcomprising the heteropolyacids or the metal salts of the heteropol acidsthat the effects of-these impurities is also .minimized possibly asaresult of the combination of .these. impurities with the catalyticagent. It is postulated that suchde- .leterious components in thecarrier'maypreferentially react with the heteropoly acid or 'itssalt toform for example such compounds as sodium phosphomolybdate, calcium'phosphomolybdate, magnesium silicomolybdate and the like,'depending ofcourseupon the heteropoly acid or-salt-employed, and in'so doingbecome-effectively isolated from the-carrier and thereby lose theirproperty of accelerating, or promoting thedegradation of the carrier.Whereas, I have foundxthat this effect is realized, the mechanismthereof'asdescribed represents only one possible explanation and is inno way intended tolimit my invention in this respect.

by the reaction, in the'first case, of-sodium phosphateandsodium'molybdate by careful acidification-and in-th second by thereaction of sodium silicateand' sodium molybdate uponacidification withhydrochloric acid. In .eithercase the extraction of theaqueous solutionof the resultant acidwith ether results in the formation of an ether.complexuwith the acid whichseparates as a ;distinctphase from the.remainder of the solution. Removal of: the other from this separatedphase' leaves the corresponding heteropoly acid. These methods, however,are to a certain extent objectionable when the acids producedare to beused inthepreparationof catalysts inasmuch as they are contaminated withsodium ionwhich are undesirable in the finished catalysts when presentinexcessive amounts. Normally purification of the acids prepared in thismanner is accomplished by :repeated recrystallization from Waterwithattendant difliculties and reduction of product yield.

In another methodof preparation of phosphomolybdic acid for example,freshly precipitated molybdenum oxide has been treatedwith phosphoricacid to yield the heteropoly acid free in this case from the undesirablesodiumion. I

withcheap readily'available chemicals to form an activestablephosphomolybdic acid. The unreacted molybdenum oxide-may of course berecycled and in this manner high yields of the heteropoly acid areobtained.

For example one batch of phosphomolybdic' acid was prepared by heatingalmost to boilingforone-half hour a mixture of 28 parts of sublimedmolybdenumpxide, 6 parts of 85% phosphoric acid, 2 parts of concentratednitric acid and ZOO-parts of water. A clear solution resulted which wasdecanted from the unreacted molybdenum" oxide which upon extraction withether yielded approximately parts of the ether acid complex whichcontained approximately 8 parts of the acid." It is apparent that thismethod of preparation is simpler and results in a purer and lessexpensiv 'product than the methods heretofore employed.

lhe recommended procedure for the purifica tion of these acids andparticularly those in which sodium ion is contained as a contaminateinvolves the isolation of the acid and recrystallization from water. Ihave found that a simpler and more economical purification is obtainedby merely washing the ether extract with dilute nitric acid two to threetimes. The washed complex may then be diluted with water andtheetherremoved by distillation, airblowing, or the like, to leave anaqueous acid concentrate free of "contaminating .ions such as sodium orchloride ions, which may be diluted and used to impregnate the catalystsas hereinafter described without further purification. Although theether tion of silicomolybdic acid since ammonium sill-H extraction-ofthe acid is not always necessary in.

order to prepare the desired catalysts, I have found that shouldtheextraction be desirable other oxygen, nitrogen or sulfur compounds whichform ccmplexes with the heteropoly acids may be used for the extractionsuch as for examplediisopropyl ether, diethylsulfide, pyridine,otherlorganic" amines and the like. Whereas, the abovedis'cussionpertaining to the preparation of the heteropoly acids has centeredprimarily} around the phosphoe and *sil'icoe molybdic. acids,suchemphasis is notintendedat'o, be indicative. of any limitations of myinvention but was. merely used for descriptivepurposes inasmuch as otherheteropoly acids such assilico.-., tungstic acid, germanovanadic acidand in gene; eral any of the earlier described heteropoly acidsmay beprepared by the method or methods; described. Still further, I, do notwishtoqbe limitedto thepreparation of any of these het eropoly acids bythe methods disclosed, inasmuch; as they may be prepared in anymannerfdesired, to be. employed in the catalysts according to my;invention However, as far as I am ,awarethel method of preparation ofthe phosphomolybdic acid, employing sublimed rather than freshlyprecipitated yellow molybdenum oxide is new in the art and as suchconstitutes a portion of the present invention. 1 i

As described above the synthesis of jsilicoa molybdic acid or othersilico-heteropoly acidsuby conventional means involves theacidification; with hydrochloric acid of a partially acidified solutionof sodium molybdate and sodium si1icate.;v Both sodium and chloride ionspresent in excesr sive amounts are deleterious to any catalysts andas aconsequence salts having ammonium or nitrate ions are employed in theirplace wherev ever possible in catalyst preparations. However," ammoniumsalts cannot be used for the prepara v cate is non-existent and ammoniumsilico-a molybdate is insoluble. The preparation ofa. low sodiumsilicomolybdic acid catalyst involves, therefore, an incomplete andcomparatively. costly ether extraction to separate ythesilicomolybdicacid from the contaminating 1011s., {Io circumvent this diniculty I mayprepare the silicomolybdic acid from sodium molybdate-and sodiumsilicate as above, employing nitric acid"- in place of hydrochloricacid. The resultant.- solution is subsequently diluted and passed;through an ion exchange to remove the sodium"? ions. The ion exchangedsolution, contains only nitric acid, silicomolybdic acid and possiblysmall I amounts of silica and molydenum trioxide gelsj. and issatisfactory as such or upon dilution or concentration to impregnatecarriers directly'orfi to be employed in the preparation ofthe'metalsalts of silicomolybdic acid, solutions of which: maysubsequently be employed to impregnate the desired carrier. Ionexchangers usable: are; hydrogen zeolite, etc. Y Y1 If it is desired toemploy as the catalytic agent a salt of a heteropoly acid rather thantheacidlitself, this salt may be readilypreparedby simple reaction of theacid with a soluble salt of the T metal ion desired. Thus for examplecobalt phosphomolybdate may be readily prepared'by simple mixing of asoluble cobalt salt such as cobalt nitrate, cobaltous fluoride, cobaltiodide} cobalt bromide, or the like, with the aque'ous phosphomolybdicacid. Alternatively thesalts may be prepared by direct synthesis withoutthe intermediate step ofacid preparation. Thus cobalt carbonate,phosphoric acid and sublimed molybdenum trioxide may be reacted and treaction products extracted with alcohohether, or the like to obtaindirectly'the cobalt phosph I molybdate complex from which the salt is'ea'sily j isolated. Further freshly precipitated cobat phosphate may bereacted with freshly precipltated molybdenum and extracted with alcoholto again obtain cobalt phosphomolybdate complex. Probably the preferredmethod of preparing 11' these salts: and. particularly the salts of thephosphomolybdicacid involves the reaction as previously described ofsublimed molybdenum trioxide with anexcess of phosphoric acidv in thepresence of a small amount of nitric acid. to yield the phosphomolybdicacid which is contaminated with unreactedphosphoric acid and tothismixture the desired. metal, ionrsuch as aluminum, zinc, colbalt, nickel,chromium. iron orthelike is addedto yield corresponding metalphosphomolybdate plus a precipitate of the corresponding metalphosphate. Such a procedure has considerable merit in that by simplecontrol ofthe amounts of the metal ions added the reaction can beemployed to remove excess phosphoric acid 'for'thepurification of theheteropoly acid or alternatively for the preparation and simultaneouspurification of the corresponding metal salt. Thus in the preparation ofthe phosphomolybdic acid as described an excess of phosphoric a'cid isemployed to accelerate the reaction between themolybdenum trioxide andthe phosphoric acid. In certain cases the presence of the excessphosphate ion is undesirable in the prepara't'ion of the finishedcatalyst and to eliminate this certain purification procedures have beendescribed such as extraction of the acid with ether or other organiccompounds capable. of forming complexes therewith, by formation ofinsoluble salts with the heteropoly acid or the,

like. Another method of purification is apparent therefore in the abovereaction whereby a sufiicient' quantity of a soluble salt, such as thenitrate, of -'a metalsuch as aluminum, zinc, iron or the like is addedto form an insolubleprecipitate of the metal phosphate from which theacid may be readily separated and employed incatalystpreparationssubstantially free from the contaminating phosphoricacid. Similarly if it is desired to form the metal salt of theheteropoly acid an excess of the soluble metal salt may be added wherebythe phosphoric acid is removed by precipitation of the phosphate and theexcess salt will react with the heteropoly acid to form a.

soluble metal salt therewith whichis substantially free of undesirablephosphate ions.

Numerous methods may be employed for the preparation of the finishedcatalysts from these acids or from the salts of the acids, the choice ofwhichv will depend upon the available facilities and. methods used inpreparing the catalytic agent and other related factors. The catalysts,according to the present invention, consist predominantly of a carrierupon which is distended in one manner oranother one or more heteropolyacidsas described, or one or more metal salts of these heteropoly acidsor a mixture of metal salts and heteropoly acids. As carriers for thesecatalysts I may employ such materials as alumina, zirconia, silica,titania, magnesia, zinc oxide, thoria,;.or the like, and as pointed outabout in general I prefer to employ the heteropoly acid or 'a salt of aheteropoly acid as the catalytic agent which contains the metal ionwhich has been found to be most suitable in conventional catalysts. Theamount of the catalytic agent distended on the carrier in each casewill, of necessity, be a function of the agent to be employed, the typeof carrier employed, and the reaction to be catalyzed. Generally,however, it has been observed that these heteropoly acids or saltsare'for a given per cent composition of the catalyst more eifectivethanan equivalent amount ofa catalytic agent comprising a metal oxide andass. result'I may employ these catalytic agents such as dehydrogenationcatalysts containing; chromium, reforming catalysts containing. vana-xdium and the desulfurization catalysts containing...

cobalt and molybdenum. I prefer to employ as, carriers for allof thesereactionsaan alumina of either highly refined natureor of less refined:nature such asbauxite. In thisrespect the usage, of the catalytic agentsherein disclosedpermits the use of the considerably less expensivebauxite in place, of the highly refined aluminaswhich have been; thoughtto be essential for suchreace t1ons as hydroforming, dehydrogenatiom(16:5

sulfurization, and the like.

The methods of preparing each of thesecatarlysts may be; divided intofour classes of" pro cedure involving impregnation, mechanical, mix.-

ing, the formation of the activecatalytic agentj in situ bythedecomposition of an organiccome-s plex thereof or the formation of theactive; catalytic agent in situ bythe decompositionof an inorganiccomplex thereof.

In the preparation of aqcatalyst by imgpregnae tion two alternativecourses-of'procedureimaygbefollowed. One involves the isolation, andpu-ri;-: fication ofthe desiredheteropolyacid or-salt-and. subsequentimmersion of the carrier-inset; water. solution of the catalyticagentfollowed-by cala.

cination to give the finalcatalyst, In, the alternative-method thecarrier may beimpregnated directly with the unpurified acidror salt;during;:

any stage of the preparation, of the catalytic agent. Thus if the ethercomplex is obtained the. carrier may be impregnated directly withthis...

complex as such preferably diluted with addie tional quantities ofether.preparational procedures, according tot-hisqine vention are followed thecarrier may be 'im--- pregnated directly with the reaction product thuseliminating thesteps of ether extraction andpurification. Thislattermethodof impregnation is particularly applicable in thosecases where theheteropoly acid or the salt of the heteropoly acid is formed in theabsence of. contaminating ions as for example asillustratedfin thepreparation of the phosphomolybdic acid directlyfrom the phosphoric acidand molybdenumtrioxide-in the presense of nitric acid. In this case theliquid product may be removed from the undisfsolved molybdenum trioxideand thecata'lyst.

carrier, in any desired form such as pellets, po wder, granules or thelike may be immersed'dl-I rectly in the liquid product inasmuch asIh'avei found that the presence 'of the nitric acid and unreactedphosphoric acid have no detrimental;

effect on the final, catalyst in most cases, 'For this reason, generallyI prefer to-usc those heteropoly acids or salts inwhich phosphoru'sfisjthe central ion of the compound .inasmuchas such acids or salts maybesoreadilyprepared.

in the absence of contaminating ionsandas are.- sult catalystpreparation is greatly cheapened.

However, it is to be understood thatflI do: notfl wish to be limited bythis method of preparation, 7 inasmuch as other acids maybepreparedfreeof contaminating ions. Thus silicomolybdic acid.

may be prepared by commingling purified silica.

However, the.-

13 gel or a silica sol, molybdenum trioxide and nitric acid and heatingthese materials to comparatively high temperatures such as above 100 C.to about 200 C. under sufficient pressure to maintain the reactingsolution in the liquid state. Further, I have found that the presence ofthe fluoride ion either as hydrogen fluoride or as the fluoride ofthemetal to be reacted has the effect of, accelerating or catalyzing theformation of v manyof theheteropoly acids. The above carriers may beused in the form oftheir oxides or the corresponding hydroxides orhydrated oxides.

The iollowing examples will serve to illustrate the preparation. ofcatalysts according to my invention by impregnation of the carriermaterial with the purified heterpoly acid or salt or with an impureheterpoly acid or salt, the latter group being preferably employed onlywhen the impurities are not detrimental or may be removed from thecatalyst by simple heat treatment.

EXAMPLE I A; catalyst comprising approximately 9.8% by weight. ofsilicomolybdic acid distended on bauxite was prepared by impregnatingbauxite with a water solution of the purified silicomolybdic acid asfollows: 100 parts of sodium molybdate was dissolved in 400 parts ofwater and heated to 60 C. after which 40 parts of concentratedhydrochloric acid was added. While rapidly stirring this solution asolution of parts of 40 Baum sodium silicate in 100 parts of H20 wasslowly added. While stirring was continued 120 parts of concentratedhydrochloric acid was added. The resultant mixture was filtered andallowed to stand for 16 hoursafter which it was decanted from the solidsand extracted with ether yielding 53 parts of an ether complex of thesilicomolybdic acid. To further purify the complex it was mixed with 50parts of water and parts of nitric acid and enough ether to separate thethird phase. Approximately '70 parts of water was added to the complexafter centrifuging and separation from the above mixture and ether wasremoved therefrom by warming and at the same time bubbling an air streamthrough the mixture. 1

A sample of 8 to mesh bauxite was calcined for two hours at 600 C. 266parts of this calcined bauxite was immersed in a solution of 173 partsof the silicomolybdic acid prepared above, diluted to 300 parts withwater. The carrier was immersed in this solution for a period of 45minutes and subsequently dried at a temperature of about 180 F. for 16hours and was activated by heat treatment for two hours at 600 C. to

yield a catalyst of the above composition.

EXAMPLE II I Another catalyst was prepared comprising approximately 8.5per cent of phosphomolybdic acid distended on bauxite as follows:Phosphomolybdic acid was prepared by heating to a temperature of about90 C. for about one hour, a mixture comprising 28 parts of sublimedmolybdenum trioxide, 6 parts of 85% phosphoric acid, 2 parts ofconcentrated nitric acid and 200 parts of water. The resultant mixturewas cooled and extracted with ether to yieldthe ether complex of thephosphomolybdic acid. The ether complex was mixed'with an equal volumeof water and the ether removed by bubbling air through the mixture undervacuum to yield the concentrated .water solution of I thephosphomolybdic acid. Approximately 306 parts of'this concen- 14 Itrated phosphomolybdic acid solution was diluted to 500 parts withdistilled water and 480 parts of 8 to 20 mesh bauxite as used in theabove Example L'which had been calcined for two hours at 600 C., wasimmersed in this solution. After a 45 minute immersion the im-.pregnated bauxite was removed from the solu-.

tion, dried for 16 hours at 200 F. and activated for two hours at 600 C.to give a catalyst of the above composition.

EXAMPLE III A catalyst comprising approximately 9%,of

titanomolybdic acid distended on a synthetic gel type alumina wasprepared in the following manner: Approximately 5 parts of freshlyprepared titania gel was slurried with 200 parts of water and 14 partsof sodium fluoride and heated to boiling. '70 parts of molybdic acidwere added together with 10 parts of sodium fluoride in the presence of100 parts of water and 100 parts of hydrochloric acid. The reactionsolution was extracted with ether to yield the ethercomplex of thetitanomolybdic acid. The acid was iso-, lated as a water solution fromthe other complex and employed to prepare the catalyst in the samemanner as shown in Examples I and II above.

It is also possible to prepare catalysts of this type without thenecessity of going through the somewhat tedious and expensive acid.purification step. Such preparation is illustrated by the followingexamples in which only a few of th 1 many possible catalysts are shown.

EXAMPLE IV A catalyst comprising approximately 11.1% by weight of zincphosphomolybdate distended on a synthetic highly purified alumina gelwas prepared as follows: 500 parts of molybdenum trioxide, 140 parts ofphosphoric acid, 35 parts of nitric acid and 2,000 parts of water weremixed and heated for approximately one-half hour at C. to yield crudephosphomolybdic acid. After separation of the solution from theunreacted molybdenum trioxide the acid was iso-- lated by etherextraction and to '75 parts of the acid in 450 parts of water 42 partsof zinc nitrate hexahydrate was added to form the zinc phosphomolybdatein acid solution. Approximately 410 parts of the synthetic alumina gelwhich had been previously calcined for two hours at 600 C., was immersedin the zinc phosphomolybdate.

solution. for a period of 85 minutes. The impregnated alumina wasremoved from the impregnated solution, dried for 16 hoursat 0.;

were made by a process similar to the above comprising cobaltphosphomolybdate on a synthetic alumina carrier, cobalt phosphotungstateon an alumina carrier and aluminum phosphomolybdate on the same carrier.

A catalyst comprising phosphomolybdic acid on bauxite was prepared byimpregnating the bauxite with the reaction products of molybdenumtrioxide, phosphoric acid, nitric acid and water extraction of thephosphomolybdic acid from the reaction product. Again it was found thatthe presence of the excess phosphoric and nitric acid had substantiallyno effect on the corresponding metallic nitrate to a portion of theabove reaction solution containing the phosphomolybdic acid withsubsequent impregnation oi bauxite with each of these metalphosphomol'ybdateso'lutions. As previously described if an excess of themetallic nitrate is employed the unreacted phosphate ion will be removedfrom the solution as an insoluble metal phosphate resulting in a purerheteropoly acid salt solution.

In another method of preparing the catalysts according to my inventionsimple mechanical mixing of the desired catalytic agent and the carriermay be employed. This procedure may be accomplished by eitherisolatingthe heteropoly acid or its salt inthedry state and subsequently mixingthe dried acid or salt with the desired quantity of alumina, silica,titania, zirconia,

magnesia, zinc oxide, thoria, mixtures of these,

or the l'ike, pil-ling or'otherwise forming the catalyst"par'ticles andcalcining at a relatively high temperature such as in the range of about300 C. to about 800 C. to yield the desired catalyst. Alternatively acalculated amount of a solution of the heteropoly acid or of the saltthereof may be mixed with a carrier so as to result in-a pastesubstantially free of excess solution which paste may be formed in anydesired shape prior to or after drying and activation. This lattermethod-diners somewhat from the method of impregnation as describedabove in that there is no excess solution and no question of separationof the carrierfrom the excess catalytic agent.

In yet another method of preparation of these.

catalysts an organic complex of the heteropoly acids may be prepared toeffect the purification of the acid or salt and this complex useddirectly to impregnate, or otherwise combine with, the desired carrier'W-hereafter the carrier is heated in the presence of air to atemperature sufficiently high to burn off the organic complex formingcompound thus leavingithe uncombined heteropoly acid or salt on thecarrier. As organic compounds for the formation of these complexes lmayuse any nitrogen, sulfur or oxygen containing organic compound which iscapable of forming a complex with the heteropoly acids, 'but I havefound that the nitrogen or amine type compounds of the structuralformula R--NH are superior for this purpose inasmuch as their usageresults i-n a more eilicient extraction of the acid or salt from thereaction solution. Thus, in the preparation of :a' catalyst comprisingfor example, chromotungstic acid, the crude reaction products:containing the chromotungstic acid as well'as contaminating iOl'lS maybe extracted with pyridine, whereby the pyridine complex of the acidseparates as a solid phase from the reaction products and may beseparated therefrom :and employed directly to combine with a carrierselected from the class described above. The catalyst is thensubsequently heated to the temperature in the range of approximately 300C. to about 300 C. for a period-of=time ranging from about one hour toabout-six hours to effect the decomposition of thepyridine-chromotungstic acidcomplex and the removal of the organicconstituents from :the catalyst by oxidation at'these temperatures.

.In a fourth method of preparing a finished catalyst employing catalyticagents of the presentlinvention, I may ."form "an inorganic -decom-Possible salt of the. desired .heteropolyi acid 'asla. means ofextracting the acid fromithe reaction solutionand employ a solution ofthis inorganic salt directly as the impregnating solution or com? binethe solid salt with the carrierandsubse+ quently calcine the impregnatedcarrier at fi-a' temperature sufficiently highto decompose-the salt andleave the heteropoly acid distended on the carrier.

may. separate the acid from thereaction: prod ucts by addition ofammonium nitrate, chlorideor the like tothereaction solution to form am:

monium'phosphomolybdate salt which is then removed as an insolubleprecipitate from the solution, dissolved in acidand the resultant sol-utionemployed directly to impregnate the desired carrier. Alternativelythe ammonium phosphomolybdate may be mixed with a-carrier in dry formand the mixture pilled or otherwise formed and heat treated to decomposethe ammonium salt to the heteropoly acid. Such usage of the inorganicsalts of the heteropoly acidispa rtic ularly desirable in the formationof ammonium the impregnation of the carrier up decomposi tion of theammonium salt upon heat treating at a temperature in the range of 300 C.to SOO C. may result'in the formation of the correspond: ingheteropolyaoid salt of such contaminating metal ions as sodium, calcium,magnesium, or the" like. As pointedout-a'bove the formation or such asalt with these contaminating ions has the ef fect of minimizing theirdeleterious effect on the destructability of the carrier. Possibly thegreat} est benefit from this method of preparation is the formation of acheap pilled catalyst. Although I have described numerous-methods ofpreparing the catalyst according to the 'pres entinventionI do not wishto be limited thereby inasmuch as the invention is directed primarily tothe newand improved catalyst and secondarily to preparation methods andtherefore other methods of preparation which may-occur-to' those skilledin the art should not be construed as falling outside the. principles ofthe present invention.

The carriers to be employed in the preparation of these catalysts willof necessity vary with the particular catalyst to be prepared. In mostpreparation procedures these carrier materials are pretreated in somemanner such as by cal cination at elevated temperatures; acid treatment,or the like to improve their characteristics in thefinal catalyst withrelation to suchfactors as surface area, :degree of purity andthe'like'.

It is within the scope of the present invention to employ anydesiredmethod of pretreating the selected carrier, .but best resultsappear to beobtained when :the carrier is at some time prior to thecompletion or the catalyst calcined at Ia tem perature in the range ofabout 300 C. to about 800 C. and preferably in the range about-500 C toabout'TOO" C. The stage at which this ca lcmationgis "most effective isdependent uponthe method of catalyst preparation employed. It

Thus in my method of preparinga phosphomolybdic acid containing catalystI A substitution may occur within the the catalytic agent is to bedistended on the carrier by means of impregnation from a solutioncontaining the catalytic agent, it is desirable to calcine the carrierat a temperature in the above range prior to the impregnation, but onthe other hand, if the catalyst is to be prepared by mixing thecatalytic agent with the carrier, the latter being either dry or ingelatinous form the calcination is most effective after the mixture hasbeen made. Although such calcination represent the preferred procedurein making these catalysts, other methods may be employed which mayalways yield effective catalysts containing the components as disclosedherein. Similarly there are many ways of treating a catalyst prior tousage to increase its activity, heat stability, mechanical strength orthe like all of which may be employed within the scope of the presentinvention. Thus the'catalysts as disclosed may be in powder form,granules, pills or any desired shape. The forming of the catalyst may beaccomplished prior to or subsequent to the combination of the catalyticagent with the carrier. In general it is preferred, in those cases wherethe catalytic agent is combined with the carrier by means ofimpregnation of the carrier from an aqueous or other solution of thecatalytic agent, to form the carrier into the desired shape prior tothis impregnation. Conversely if the catalytic agent and carrier are tobe combined by mechanical mixing it is preferable to form the catalystafter the combinationhas been affected. Also in most cases I have foundthat best catalytic results are obtained if the combined carrier. andcatalytic agent, he, the catalyst is heated to a temperature in therange between. about 300 C. and about 800 C. for a period of from about1 to about 4 hours. The preferred temperatures for this heat treatmentlie between about 400 C. and about 650 C. and the optimum timeoftreatmen-t has been found to be about Z'hours. It is to beemphasizedthat these considerations ar not to be construed asestablishing limitations of the present inventioninasmuch as any methodof treating the catalyst maybe employed dependent upon the choice of theindividual uses.

In many catalytic reactions a catalyst is employed which may be said tobe comprised substantially completely of the catalytic agent in theabsence of any carrier or supporting material. Such usage is illustratedfor example in the desulfurizationof sulfur containing hydrocarbonswherein a mixture of the combined oxides of cobalt and molydenum hasbeen employed in the absence of supporting alumina or other carriers.Suchcatalysts may also be prepared and used according to the presentinvention by calcining theacids-or salts as herein disclosed in theabsence of carrier material. I have found. that such: application ismore effective with the metal salts of the heteropoly acids than withthe acids themselves and particularly those. metal salts in which thesalt forming metal ion is selected from the class of elements comprisingalumina, zirconia, titania, magnesia, cobalt oxide, thoria, or the likeare the most satisfactory. Thus such catalysts as cobaltphosphomolybdate, "cobalt phosphovanadate, cobalt silicontungstate, andthe like are effective desulfurizationcatalysts while siichcatalysts ss-aluminum boromolybdate, aluminum phosphomolybdate; titanium phospho-Inplybdate ferric; silicomolybdate, and the like are fi ct ye hydr formnsca s; e c; L

The foregoing description illustrates the type of catalysts and methodsof preparing these catalysts which I may employ to catalyze hightemperature hydrocarbon conversion "processes such as the hydrogenexchange processes including dehydrogenation, desulfurization,hydrogenation, hydroforming, aromatization, and'the like, molecularreforming processes such as cracking, alkylation, desulfurization,condensation, and the like, addition processes such as nitration,chlorination, bromonation, hydration, and the like, and isomerizationprocesses, which conversion processes are generally carried out attemperatures in the range of about 50 F. and to about 1500 F. and atpressures in the range of about --14 pounds persquare inch to as high as1,000 pounds per square inch or higher. For these processes, I mayemploy catalysts comprising a catalytic agent consisting of theheteropoly acid or a salt of the heteropoly acid which catalytic agentmay or may not be distended on a suitable carrier. The preferredcatalysts according to the present invention comprise the heteropolyacids or the salts of the heteropoly acids, and preferably those acidsor salts containing phosphorus as the central ion, as the catalyticagents distended on alumina of either natural or synthetic origin.

Thus in the process known as hydrof-orming a selected hydrocarbon feed isubjected to the action of the catalyst at temperatures in the range ofabout 700 F. to about 1200 F., and preferably in the range of about 850F. to about 1050 F., and at pressures of about to about 500 pounds persquare inch or higher in the presence of a hydrogen'ri-ch recycle gaswhereby a substantial portion of the hydrocarbon feed is converted toaromatic hydrocarbons. Also in a hydrocarbon" conversion process knownas desulfurization sulfur containing hydrocarbons are passed over thecatalyst at temperatures rangin f-romas low as about 500 F. to as highas about 1,000 F. but preferably in the range of about 600 F. to about900 F. and at pressures in the range of a few atmospheres to about 1,000pounds per square inch or higher. The desulfurization is more completeif the reaction is carried out in the presence of a hydrogen richrecycle gas.

The dehydrogenation of the normally gaseous.

hydrocarbons as well as the normally liquid hydrocarbons in the presenceof catalysts of the present invention may be carried out at temperaturesin the range of about 900 F. to about 1500 F. and preferably in therange of about 1,000 F.

r to about 1,200 E. at pressures in the range of ll pounds per squareinch to atmospheric or above. In the dehydrogenation of certainhydrocarbons particularly those containing an unsaturated linkage it maybe desirable to include in the feed to the reaction an inert diluentsuch as steam, nitrogen, carbon dioxide or the like, or a gas which mayfunction as a hydrogen acceptor such as a lower molecular weight olefin,diolefin, or the like.

In certain of its aspects the process of arcmatization is analogous tothe process of dehydrogenation and hydroforming, and for this reason thepreferred catalysts for the aromatization reaction are those in whichthe catalytic agent comprises a heteropoly acid or a heteropoly acidsalt containing both chromium and molybdenum such as for examplechromium phosphomolybdate, chromiomolybdic acid, chromiumgermanemolybdate, chromium arsenomolybdate, and the 1'9? like. In theprocess of aromati'zation the hydrocarbon feed, normally substantiallyparafilnic in nature, is passed over. the catalyst at a temperature intherangeof'about. 600 F; to about 1,000 F. and preferably in the. rangeof about 700 F. to about 900 F. at pressuresin the range of aboutatmospheric to 100 pounds per square inch or greater. Thearomatizationreaction may be carried out either in the presence orabsence of a hydrogen rich recycle gas.

l he following examples represent the'uti'lization of only a fewof thecatalysts prepared according to the present invention, butareillustrative of the merits of these catalysts.

Two hydroforming' catalysts were prepared using a low iron contentbauxite as a carrier upon which was distended in one case 10.0 weightper centof molybdenum trioxide and in the other 8.4 weight per cent of.phosphomolybdic acid. Catalyst No. 1- comprising the molybdenum trioxidedistended on bauxite was prepared by in mersing- 250 parts by weight oflow iron content bauxite of 820 mesh size in 250 parts of impregnatingsolution. This impregnating solution was prepared by dissolving 65 partsof ammonium paramolybdate (analyzing 81.8% M003) in parts of 0.9specific gravity ammonium hydroxn ide. Fifty parts. of water were addedto the ammonium hydroxide solution, the resultant solution filtered.and. diluted with water to yield 250 parts or". the impregnatingsolution. After 15 minutes immersion time. the impregnated bauxite wasremoved from the solution, dried for 16 hours atapproximately 110. C-and heated for two hours in an atmosphereof air .at 600 C. to convertthe adsorbed ammonium m'olybdate to molybdenum. trioxide. The finishedcatalyst designated as"Catalyst No. 1 analyzed 10.0 weight per cent ofM003 on the bauxite carrier. Catalyst No. 2 was prepared by immersing asample of the same bauxite in an aqueous solution of phosphomolybdicacid as. follows: The phosphomolybdic acid was prepared by heating. amixture comprising 600. parts by weight of sublimed molybdenum trioxide,110 parts of orthophosphoric acid, 100 parts of concentrated nitricacid. and 1,000 parts of water to 65-85 C. for three hours accompaniedby continual agitation. The supernatant liquid wasv decanted from theunreacted M003, filtered and extracted with ether to yield approximately110 parts by Weight of the ether complex of the acid. This complex wasdissolved in an equal volume of water and the ether was removed bybubbling air through the solution under vacuum. The resultingconcentrate was diluted with -water to the ratio of 243 parts ofphosphomolybdic acid to 250 parts of water and the catalyst was preparedby immersing 500 parts of 8-20 mesh, low iron bauxite in 555 parts ofthis solution for 2 hours, drained, dried for 16 hours at 110 C. andheated for two hours to 600 C. The finished catalyst contained 8.4 percent by weight or phosphornolybdic acid.

Catalysts 1 and 2 were tested for hydroforming activity when fresh andafter a heat treatment for six hours at 800 C. by passing a feedcomprising a 200 F. to 260 F. boiling range naphtha fraction over eachcatalyst sample at 950 isothermal block temperature, 100 pounds persquare inch gage pressure, at a'liquid hourly space velo'c ity of 1.0and with 3,000 cubic feet of hydrogen rich recycle gas per barrel offeed. The aromatic synthesis reported'in; Table 1 was taken in each caseas a measureof theyhydroforming activity of each catalyst;

Ta'hZeNo. 1

Further the heat stability of Catalyst No; 2 is:

considerably better than that of; Catalyst No. 1, the formerlosingjapproximately 12% of its freshv activity as. compared to a lossof approximately 43% suffered by the latter; As previously described theimprovement of heat. stability is attributed to the use'of themolybdenum in com.- bined form whereby it may beconsidered. to be. lessavailable to acceleratetheloss in activity of the carrier- Yet another.advantage of the, catalysts of the presentinvention is, evidenced bythe. data of Table 1, that being the reduction of the. crackingcharacteristics. of the catalyst. This eifect is apparent bycomparisonjof the 68.6% liquid yield from Catalyst No. 1 and'th-e 77.2%

liquid yield from Catalyst No. 2; at substantially the same level ofhydrof'orming activity.

EXAMPLE VI- A third hydroforming catalyst comprising silicomolybdic aciddistended on low iron content bauxite was prepared, as follows: 300parts of sodium molybdate was dissolved into 1200 parts of water towhich solution wasadol'ed 120 parts of concentrated hydrochloric acid.This solution was vigorously stirred and 30 parts of 10 Baum sodiumsilicate dissolved in 300 parts of water was slowly added. Subsequent;to this addition 360 parts, of concentrated hydrochloric acid was addedto the mixture. The resultant solution was extracted with ether to givethe ether acid complex. 'The ether'complexcontaining sodium ion as animpurity was washed twice with a solution of 3 to 1 dilution-ofconcentrated nitric acid; An equal volume of waterwas added to thepurified extract and the ether removed by bubbling air through themixture under vacuum. A catalyst was prepared by immersing 500 parts ofthe 8 to 20 mesh low iron bauxite employed in the preparationofCatalysts 1 and 2' in a solution comprising267 parts of a silicomolybdicacidwater concentrate diluted to 5515 parts with water. After animmersiontime or 2. /2 hours the. impregnated bauxite was. drained: anddried for 16 hours at C;.'a'nd subsequently heattreated for two hours at600- C. "The resultant catalyst designated Catalyst No. 3comprisedapproximately 8% by weight of. silicomolybdic acid distended onthe 8130-20 mesh bauxite. This catalyst was tested for hydroiormingactivity according to the procedure outlined in Example V when fresh andafter asix hour heattreatment at 800 C. The results of theseactivatio'nftests are given in Table 2 in which the activity. data forCatalyst No. 1 is repeated for purposes of comparison.

Table No. 2

Catalyst No. 1 Catalyst No. 3

M003, Wt. percent 10.0 10.0 1 8. 0 1 8.0 Heat Treatment Temp, "C Fresh800 Fresh 800 Test Data:

Product Yield, vol. percent 68.6 83. 7 68.4 77.2 Product Gravity, A. P.I... 42. 0 50. 3 41. 6 44. 6 Synthetic Aromatics, Vol.

percent 34. 3 19. 6 35.1 34. 2

1 Present as silicomolybdic acid.

It is seen from these data that the combination of the molybdenum withthe silica in the form of silicomolybdic acid greatly improves the heatstability of the catalyst as evidenced by a loss of activity of thesilicomolybdic acid catalyst of some 2% and of the molbydenum trioxidecatalyst of 43%. Further, by comparison of the data for Catalyst No. 3and the data for Catalyst No. 2 the latter containing phosphomolybdicacid, it is apparent from the yield values and product gravities thatthe presence of the silica induces a destruction of the feed greaterthan that of the phosphorus containing heteropoly molybdic acid.However, this destruction due to the presence of silica is notsubstantially different from that occurring when employing molybdenumtrioxide as the catalytic agent as evidenced by the gravities and theyields shown for the fresh catalyst No. 1.

EXAMPLE VII Another effective hydroforming catalyst utilizes thealuminum salt of the phosphomolybdic acid as the catalytic agent. Toprepare such a catalyst 32 parts of aluminum nitrate was dissolved in asolution of 224 parts of phosphomolybdic acid concentrate diluted to atotal of 555 parts with water. 555 parts of the same 8 to 20 mesh lowiron bauxite was immersed in this solution for 110 minutes subsequentlydrained, dried for 16 hours at approximately 100 C. and heat treated fortwo hours at 600 C. This catalyst was tested for hydroforming activityas in the above example yielding a synthesis of aromatics ofapproximately 34% when fresh and approximately 33.1% after heattreatment at 800 C. for six hours. It was found that the activity andheat stability of this catalyst which comprised approximately 9.0% ofaluminum phosphomolybdate distended on the low iron bauxite, issubstantially equal to the heat stability and activity of thephosphomolybdic acid and silicomolybdic acid catalysts.

EXAMPLE VIII Two desulfurization catalysts were prepared, one comprisingthe combined oxides of cobalt and molybdena distended on a gel typealumina, and the other cobalt phosphomolybdate distended on the samealuminum. Catalyst No. 4 comprising the combined oxides of cobalt andmolybdena distended on alumina was prepared by impregnation of thealumina carrier with a solution containing salts of cobalt andmolybdenum. This impregnation solution was prepared as follows: 173parts by weight of ammonium paramolybdate containing 82.2% of molybdenumtrioxide was dissolved in a solution of 450 parts by weight of .9specific gravity ammonium hydroxide and 300 parts of water. To thisammonium molybdate in ammoniacal solution was added 150 parts by weightof a 3.43 molar cobalt nitrate solution.

The catalyst was prepared by immersing 300 parts of 8 to 20 meshsynthetic alumina gel, which had been previously heat treated for twohours at 600 C., in 400 parts of the above impregnating solution. Afterfifteen minutes immersion the impregnated alumina granules were drained,dried for sixteen hours at approximately 110 C. and heat treated for twohours at 600 C. to yield the final catalyst comprising approximately9.7% of the combined oxides of cobalt and molybdenum and approximately90.3% by weight of alumina.

Catalyst No. 5 comprising approximately 9% of cobalt phosphomolybdate onthe same syn thetic gel type alumina was prepared as follows: 36a partsof a concentrated phosphomolybdic acid solution was mixed with 59 partsof cobalt nitrate hexahydrate and this mixture diluted with water togive a total of 700 parts by weight. 575 parts of the 8 to 20 meshalumina previously heat treated for two hours at 600 C; was immersed inthe solution of cobalt phosphomolybdate for 45 minutes. The impregnatedalumina was drained, dried for approximately 16 hours at C. and heattreated for two hours at 600 0.

Each of these catalysts was employed to desulfurize a heavy straight rungas oil with a boiling range of 395 F. to 650 F. and containing 2.28weight per cent of sulfur determined by the ASTM bomb method. A six hourrun was made with a sample of each catalyst as prepared and after an 800C., six hour heat treatment. The conditions of operation were a liquidhourly space velocity of 2, a pressure of 150 pounds per square inchgage, 750 F. isothermal block temperature and with 3,000 cubic feet of:a hydrogen rich recycle gas per barrel of feed. It is realized thatthese conditions of operation are not optimum for gas-oildesulfurization inasmuch as an increase in pressure or a reduction inspace velocity will affect a greater degree of sulfur removal but werearbitrarily chosen for standard test conditions. The results of theseactivated tests are tabulated in TableB below:

1 Present as cobalt phosphomolybdate.

EXAMPLE IX 7 Another desulfurization catalyst was prepared in a mannersimilar to that of Catalyst No. i comprising approximately 7.9% byweight of the combined oxides of cobalt and molybdenum distended on 8 to20 mesh low iron content bauxite and is designated Catalyst No. 6.Catalyst No. 7 comprising approximately 8% by weight of ferricphosphomolybdate distended on the same bauxits was prepared as follows:206 parts of phosphomolybdic acid concentrate, 30 parts. of concentratednitric acid and 61 parts of ferric nitrate (Fe(NOs)3'9Il2C) weredissolved and diluted to 480 parts with water. 500 parts of the 8 to 20mesh bauxite was immersed in this solution of ferric phosphomolybdatefor 80 minutes. The impregnated bauxite was drained, dried for 16 hoursat C. and heat treated for two hours at 600 (3. Each of these catalystswas tested for desulfurization activity as in Example VII when fresh andafter heat treatment at 800 C. for six Catalyst No. 6 Catalyst No. 7

Catalytic agent, we 7. 9 2 7. 9, 2 S. 2 8.0 Heattreatment C Fresh 5300Fresh 800 S in product, Weigh 182 2 70 190 203 1 Present as cobaltmolybdate. 2 Present as ferric phosphomolybdate.

t is apparent from ExamplesVII and VIII that the catalysts of thepresent invention in which the cobalt and molybdenum or iron andmolybdenum are present on the catalyst in the form of a heteropoly saltyield a catalyst of greater heat stability than when the catalytic agentconsists simply of the combined oxides of the metals.

Catalysts oi the above type, comprising iron, cobalt and nickel or othergroup VIII metal salts of the heteropoly acids, are especially suitablefor addition reactions, such as hydration or aminination of olefins toproduce alcohols or amines. The latter reactions are generally carriedout at temperatures in the lower portion of the above range, for exampleabout 506 to 700 R, at rela-- tively high pressures, such-as about 500to about 5909 pounds per square inch, in the presence of water orammonia respectively, in amounts between about 10% and 75% of thegaseous feed mixture. Thus the cobalt phosphomolybdate Catalyst N0. 5above was used for hydration of propylene at a temperature of 500 F. anda pressure of 509 pounds using 50% water vapor in the feed, to obtain ayield of about isoprop'anol, substantially the equilibrium value.Similarly, at 556 F; and 1600 pounds gage, a steam, 75% ethylene feedwas used'to obtain a yield of about 2.5%, also very ear the maximumtheoretical value. With Catalyst No. '7, the iron phosphomolybdate onbauxite, results almost as good were obtained. A nickel'phosphomolybdate on bauxite Was prepared in a manner entirely similarto Catalyst No. 7 using nickel nitrate in place of the ferric nitrate.The resulting catalyst was employed in the preparation oiisopropyl aminefrom propylene. In this reaction, a temperature oi about 600 F. wasemployed, a pressure of I about 500 pounds gage, and a gaseouscomposition containing about equal parts of ammonia and propylene asfeed. The conversion to the amine was about 75 of the theoretical. Acobalt silico-molybdate on alumina catalyst was prepared by impregnatingthe alumina solution containing sodium molybdate and sodium silicatepartially acidified with nitric acid and subsequently passed through acommercial ion exchanged resin to convert the sodium ions to hydrogenions prior to impregnation. Following the impregnation of the abovesolution, and drying, the impregnated alumina was dipped in a solutionof cobalt nitrate to convert the silicomolybdic acid to cobaltsilicomolybdate. The resulting catalyst was used in the conversion ofthe butenes a refinery butane-butene mixture, bypassing a mixturecontaining about equal parts of ammonia and the refinery butane-butenemixture over the above catalysts at a temperatureof about 500F. and apressure of about too pounds gage. The product contained a substantialproportion of butyl amines and unconverted butane. Similar good-resultsare obtain- 24 able for addition reactions, using the other group VIIImetal salts of the heteropoly acids.

It is to be understood that these examples are not intended tolimit myinvention inasmuch as other catalysts have been prepared and used inthese and other hydrocarbon conversion processes and the presentinvention includes the usage and preparation of catalysts comprising aheteropoly acid or a heteropoly acid salt either distended on a suitablecarrier or in itself for catalysts for the hydrocarbon conversionprocess.

This application is a continuation-in-part of my copending applicationSerialNo. 619,693, filed October 1, 1945 now U. S. Patent 2,547,330.

Having described and illustrated the principles of my invention andrealizing that many mo-tli fications thereof may occur to thoseskilledin the art without'departing from the spirit and scope of theinvention, I claim:

1. A catalyst consisting essentially of a major proportion of a carrierof the group consisting of the inorganic metal oxides and hydroxides andimpregnatedthereon a minor proportion between about 3% and about 20% ofa nickel salt of a heteropoly acid.

2. Acatalyst consisting essentially of a major proportion of acarrierselected from the class of compounds consisting of "the inorganicmetal oxides and hydroxides and impregnated thereon a minor proportionbetween about 3% and about 20% of a compound selected from the class or"the zinc, iron, cobalt and nickel metal salts of the heteropoly acids.

3. A catalyst according to claim 2 in which the heteropoly acid containsmolybdenum.

4. A catalyst according to claim 2 in which the compound present'inminor proportion is a metal salt of a heteropoly acid in which thecentral atom is phosphorus.

-5. A catalystconsisting essentially of a major proportion of a carrierselected from the class of compounds consisting of the inorganic metaloxides and hydroxides and impregnated thereon minor proportion betweenabout 3% and about 20%01 a cobalt salt of a heteropoly acid.

6. A catalyst'consisting essentially of a major proportion'of a carrierselected from the class of compounds consisting of the inorganic metaloxides and-hydroxides and im regnated thereon a minor proportion betweenabout 3% and about 20% of a zinc salt of a heteropoly acid.

7.1% catalystconsisting essentially of a major proportion of alumina andimpregnated'thereon a minorproporvion between about 3% and about 20% ofa nickel salt of phosphomolybdic acid.

'8. A catalyst consisting essentially oi'a major proportion of aluminaand impregnated there on a minor proportion between about 3% about 20%of cobalt phosphornolybdate.

9. A catalyst consisting essentially of a major proportion of aluminaand impregnated thereon a minor proportion between about 3% and about20% of cobalt silicomolybdate.

1i). A method of preparing a catalyst comprising'a metal salt ofphosphomolybdic acid distended on alumina which comprises comminglingsublimed molybdenum trioxide, phosphoric acid, nitric acid and water,heating the resultant mixture'to' a temperature in the range of about 60C.,to' about C. for a period of about 1 hour to about 5 hours to formphosphomolybdic acid therein, adding thereto a suiiicient amount of awater-soluble salt of the desired metal to form the desiredphosphomolybdic acid salt, immersing said alumina carrier intheresultant solution 25 whereupon a portion of the phosphomolybdic acidsalt in said solution is adsorbed by said alumina carrier, drying saidimpregnated alumina carrier at a temperature of about 100 C. and heattreating said carrier at a temperature in the range of about 400 C. toabout 800 C.

11. In a method of preparing a material selected from the groupconsisting of silicomolybdic acid, silicotungstic acid, phosphomolybdicacid, and phosphotungstic acid, and metal salts of said acids, whereinsaid metal salts are formed by adding to an aqeous solution of saidacids a water-soluble salt of the desired metal, the improvement whichcomprises forming said aqueous solution of said acids by dissolving onesoluble salt selected from the group consisting of the soluble metalmolybdates and tungstates with a second soluble salt selected from thegroup consisting of the soluble metal silicates and phosphates, andtreating the resultant solution with a solid ion exchanger to convertthe cation to hydrogen ion.

12. A catalyst according to claim 2 in which the carrier consistsessentially of alumina.

13. A catalyst according to claim 12 in which the heteropoly acid is amolybdenum-containing heteropoly acid.

14. A catalystaccording to claim 13 in which the heteropoly acid is aphosphomolybdic acid.

15. A catalyst according to claim 14 in which the compound is a zincsalt of phosphomolybdic 16. A catalyst consisting essentially of a majorproportion of a carrier of the group consisting of the inorganic metaloxides and hydroxides, and impregnated thereon a minor proportionbetween about 3% and about 20% of an iron salt of amolybdenum-containing heteropoly acid.

RAYMOND N.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS OTHER REFERENCES Kingman et al.: Nature, March 28,1936 pg. 529.

1. A CATALYST CONSISTING ESSENTIALLY OF A MAJOR PROPORTION OF A CARRIEROF THE GROUP CONSISTING OF THE INORGANIC METAL OXIDES AND HYDROXIDES ANDIMPREGNATED THEREON A MINOR PROPORTION BETWEEN ABOUT 3% AND ABOUT 20% OFA NICKEL SALT OF A HETEROPOLY ACID.